Torque regulator for compressed air operated hand tools and other motors



Nov. 18 1958 A. HEIDLER 2,350,603

TORQUE REGULATOR FOR COMPRESSED AIR OPERATED HAND TOOLS AND OTHER MOTORS Filed Dec. 15, 1954 4 sheets sheet 1 1 a 65 4 Z g 341 e7 10 I: a? ii 5 ea a J l J J6 J Q 66 35- a? g T R R invanfol" if R? ALBERT #Emag A. LJLQQL'M J w Nov. 18, 1958 A. HEIDLER 2,860,603

TORQUE REGULATOR FOR COMPRESSED AIR OPERATED HAND TOOLS AND OTHER MOTORS Filed Dec. 13, 1954 4 Sheets-Sheet 2 I k\\ g i I l i I I E i 4 3- g /n Vin/on 44 597 HE/DLE E/ Nov. 18, 1958 A HEIDLER 2,860,603

TORQUE REGULATOR FOR COMPRESSED AIR OPERATED HAND TOOLS AND OTHER MOTORS Filed Dec. 13, 1954 4 Sheets-Sheet 3 /nven for 4 Sheets-Sheet 4 AIR OPERATE A. HEIDLER HAND TOOLS AND OTHER MOTORS Nov. 18, 1958 TORQUE REGULATOR FOR COMPRESSED Filed Dec. 15, 1954 INVENTOR Albert Heidler klhmg x ATTORNEY United States Patent TORQUE REGULATOR FOR COMPRESSED AIR OPERATED HAND TOOLS AND OTHER MOTORS Albert Heidler, Eltville, Rhineland, Germany Application December 13, 1954, Serial No. 474,825

Claims priority, application Germany December 12, 1953 Claims. (Cl. 121-34) This invention relates to compressed air operated rotary tools, such as drilling machines, grinding machines, screwtightening machines and the like which are usually equipped with centrifugal governors in order to avoid excessive speeds of rotation under no-load conditions. Despite these governors, the speed under full-load is about 30-40% below the idling speed, because the tools are used both in a horizontal and in a vertical position and the governors must consequently operate reliably in each position and therefore a large range of adjustment must be available.

The high no-load speed involves an unnecessarily high air consumption and wear and the result is that with grinding machines the permissible maximum peripheral speed of the grinding wheels cannot be utilised, because the maximum permissible grinding wheel diameter has to be given dimensions according to the high speed which occurs, that is to say, according to the no-load or idling speed. The grinding wheels consequently can only be used at about 60 to 70% of their permissible speed. In order that the idling speed may be better adapted to the speed under load, attempts have already been made with stationary grinding machines to regulate the supply of compressed air in dependence upon the torque transmitted to the grinding wheel, i. e. upon the load condition expected of the latter. For this purpose a compressed air motor has been rotatably arranged relatively to a stationary machine frame and relatively to a grinding wheel to be driven. Such a torque governor, however, necessitates an assembly of at least three coaxial parts which are rotatable relatively to one another and thus may be considered available for use with heavy stationary machines.

It is the object of the invention to obviate the disadvantages of the known centrifugal governors and torque governors.

According to the invention, the driven shaft of the motor consists of two sections which are coupled together, so as to be displaceable relatively to one another, by means of an intermediate element in dependence upon the torque taken from the motor through the driven shaft, the axial displacement being transmitted to a regulator valve. Due to the axial displacement of the shaft sections relatively to one another, a torque regulator according to the invention is suitable for any tool which supplies a driving torque and which has an attached motor, irrespective of whether stationary machines or portable tools are concerned. The regulating step is completely independent of the position and movement of the motor of the regulator and of the tool as regards the surrounding parts. Moreover, the regulator is arranged completely within the casing of the appliance and it is possible similarly for the motor to be fixedly mounted and enclosed within the appliance, whereby it is ensured that the latter has a considerably greater effective life, is reliable in operation and fool-proof. Furthermore, by conversion of the driving torque transmitted by the driven shaft into an axial displacement, it is possible for the regulator 2,860,603 Patented Nov. 18, 1958 .2 according to the invention, to be adapted to a wide variety of control conditions.

In a preferred embodiment of the invention the intermediate element or coupling permitting relative displacement of the shaft sections relatively to one another due to the applied torque contains at least one helical key disposed in a suitable groove. It is expedient to provide a spring, adjustable as to its initial tension and adapted to act against the axial displacement of the shaft sections produced by the torque of the driven shaft.

According to one embodiment of the invention, the tw shaft sections are axially moved together by their coupling as the torque increases and thereby open or close a regulator air valve to a greater or lesser extent. This embodiment of the torque regulator according to the invention is in particular more suitable for use with grinding machines, drilling machines, milling machines, planing machines and the like.

Another embodiment of the invention, particularly of advantage when used with mechanical screwdrivers and impact-type wrenches, provides that the regulator air valve is opened when the torque is small and closed when a predetermined torque is exceeded, so that the machine comes to a stop.

The abutment point of a piston embodied in the regulator is variable expediently by an adjusting knob or a similar device arranged externally on the machine in order that adjustment may be effected and the machine stopped at the required torque value. Moreover, provision may also be made for the piston to travel by means of a control edge over an air supply passage and thereby to be automatically controlled, this closed position being maintained until the operator has closed the inlet valve, or by an additional levering action of the control piston has brought the inlet valve from the closed into the open position.

The constructional examples of torque regulators according to the invention are hereinafter described with reference to the accompanying drawings, wherein:

Figures 1 and 2 show in longitudinal section a torque regulator for a compressed air hand grinding machine.

Figures 3 and 4 show in section another embodiment of a torque regulator, which may be used for piston engines in conjunction with a valve.

Figures 5 and 6 show a regulator air valve for impacttype wrenches.

Fig. 7 shows a modification of an air valve arrangement in which the unit may be restarted by a push button control.

One embodiment of a compressed air hand grinding machine with a regulator according to the .invention is shown by way of example and in longitudinal section in Figures 1 and 2, the motor being designed as a laminated motor. Figure 1 shows the machine in the no-load position and Figure 2 shows it in the full-load position. The admission valve and the grinding wheels are omitted in the figures.

The compressed air enters the housing 2, 3 at 1 and is conveyed through bores 4, 5, 6 and 7 to the rotor 8 mounted in ball bearings 9 and 10 in the rotor covers 11 and 12. In conjunction with a rotor bushing 13 and plates or lamellae 14, the rotor forms an eccentric annular chamber which is subdivided into segments and in which the compressed air drives the rotor 8 in known manner and then escapes through bores 15. The rotor 8 has a central bore 16, in the enlarged portion 17 of which is located a compression spring 18. The bore 16 is also enlarged at its other end, where it is formed with an internal rifling 19 with a pitch of about 70 to in relation to the plane of rotation. Movably arranged in this internal rifling is a coupling element 20 i with a corresponding external rifling, the element being formed at its other end as a splined shaft 21 disposed for sliding movement in a coupling sleeve 22 which in turn is fixed on the grinder shaft 23 which carries a grinding wheel, not shown.

The coupling element 20, 21 is shown in elevation in Figure 1 and in section in Figure 2. A bolt 24 is fixed bymean's of a spring washer 25 and a nut 26 in the central bore 36 (Figure 2) of said coupling element. The bolt 24, in conjunction with the coupling element 20, 21 thus forms a single component. At the opposite end, the bolt 24 carries a collar 27, the compression spring 18 hearing against one side of the collar, which on the other hand limits the axial movement of thecoupling'ele'ment 20, 21 when it bears on the end face- 6f the rotor 8, as shown in Figure 2. The axial movement of the coupling element"20,"21 is limited in the other direction by the fact that its end face 28 (Figure "1) bears on the internal end surface 29 of the rotor 8. Located in a regulator housing 30 is a regulator piston 31 urged by a weak compression spring 32 by way of a pin 33 against an adjustable stop 34 screwed in the bolt 24 to follow the latter in its movement. A nut 35 is used for fixing the adjusted position of the stop 34.

If the air inlet is opened by the admission valve, not shown, it is only possible initially (Figure 1) for a small amount of compressed air to pass through the regulator valve 30, 31 and an opening segment 37 to reach the rotor 8 in order to drive the latter. The regulator is thus in the idling or no-load position. The speed of rotation required forthe idle running may be adjusted asfde'sire'd by making the opening segment 37 of suitable size, for example, by means of the stop screw 34. It may either be adjusted so that it is equal to the fullload speed or so that it is slower than the latter. It is expedient to provide an idle running speed which is slower than the full-load speed in order to reduce con- 'sun'lption of air and wear during idle running.

"As soon as the grinding wheel is brought against a workpiece and meets resistance on the latter, the bolt 24 and "regulator piston -31 carry out a slight longitudinal movement due to the co-operation of the coupling element 20 with the internal rifling of the rotor and with the compression spring 1'8, whereby more compressed air is able to flow to the rotor. The greater the resistance, the "greater is the torque to be transmitted through the coupling element 20, 21 and the greater is the extent to which the regulator throttle valve is opened and the greater is the compressed air energy available for overcoming the greater torque and for the application of greater power to flow to the rotor. Therefore, a larger opening of the inlet throttle valve corresponds to each increase in torque in the driving shaft. The valve at its "full opening corresponds to the torque at full-load and to 'therated output of the machine. The machine reaches its maximum speed with maximum load and im- 'me'diately reverts to 'a lower speed at no-load.

An'other construction of regulator which may be employed for piston engines is shown in Figure 3 in an idling position and in Figure 4 in a full-load position. With this construction the regulator is arranged in a secondary shaft. The drive is from the spur gear 38 by way of the 'hollow shaft 39 with internal rifting 40 and'a displaceableshaft 41 with external rifling 42 and is transmitted by teeth 43 to adriven spur .gear 44. In the idling position (Figure 3), when no great torque is to be transmitted, theinternal shaft 41 bears with a shoulder 46 on the end of the hollow shaft 39 owing to the pressure of a spring 45. As soon as higher torques are to be transmitted, the 'spring45 is increasingly compressed due to relative movement between the two parts 39 and 41 to the rifiing 40, 42, and, underfull-load a bolt 47 bears with'its' shoulder 48against the inside surface 49 of a'sc'rew cap 50. During'axial movement of the internalshaft 41, the teeth'43-slide in the driven gear wheel 44 fixed in an axial direction. A thrust pin 47a transmits axial movements of the internal shaft, as in Figures 1 and 2 or by way of a lever system, to a regulator valve.

With screw-tightening machines and impact-type wrenches, those parts which convert the turning moment in the driven shaft into an axial movement, that is to say, the rifled parts in Figures 14, may be retained with the difference that axial thrust preferably takes place in the opposite direction. On the other hand, the regulator valve in such machines is of a design to conform with its purpose. One example of a construction of such a regulator air valve, especially for impact-type wrenches, is shown in Figure 5 in the open position and in Figure 6 in the closed position. A bushing 51 is fixed in the housing 2 to coincide with the air inlet 1, and a piston 52 is held by a compression spring 53 in its end position in the said bushing (see Figure 5). As soon as the inlet valve (not shown) is opened and is held in the open position, for example, manually, during the operation, the compressed air flows by way of an annular chamber 54 to the passage 5 and then to the rotor, as in Figure 1. At the same time, a component air stream flows through the duct 61 to an annular chamber 62. As the torque increases, the adjustable stop screw 34 is displaced, as described above, towards the adjusting spindle 56, which in turn displaces the piston 52 by way of a screw-thread connection 57 against the pressure of a spring 53 until the edge 55 of the piston 52 reaches the annular chamber 62 when a specific torque will obtain. At this instant, compressed air flows into the chamber 63 and displaces the piston 52 to a greater extent against the pressure of the spring 53'until it shuts against a bushing 60 (Figure 6), whereby the air supply by way of the passage 5 to the rotor is shut oif and the machine stops. If the supply of air to the passage 1 is shut off by releasing (closing) the inlet valve (not shown) the compressed air which until then has been present in the chamber 63 and which has held the valve parts 51, 52 in the closed position escapes through a small bore 64 which provides a leak to atmosphere and the valve parts 51, 52 again assume the ready position, so that the operation may start afresh when the inlet valve is opened again. By axial adjustment of the adjusting spindle 56 by'means of an adjusting knob 59 on engaging a square section 58, it is possible to arrange for the switching-01f process to take place at any desired torque in the driven "shafts.

In such devices'which are switched offwhen they reach their maximum capacity, the regulator air valve can also be "provided with an additional lever mechanism by means of which the valve'can be brought into its open position without closing the main valve.

In a similar manner, the regulator may also be employed with motors of a different type, and also with stationary and portable machine as well as hand tools. It is always expedient to use such a regulator when it is'desired to provide a control which is dependent 'on torque or when the characteristic of the motor supplies an automatic adjustment to a low speed with a small output of the regulator. For example, in explosion motors the regulator air valve may be inserted in the conduit between carburetor and cylinder 'or in internal combustion engines inthe fuel pipe.

In the modification shown in Fig. 7 an additional push button control is provided. When in the illustrated state the piston 52 is in the end position on the right hand, whereby the supply of compressed air is shut off, and the machine is stopped to start again, it is not necessary to close the inlet'valve andto reopen it, but pressure to the push button valve 65 permits the discharge of air from the chamber 63, by way of channel 66, while channel "61 is closed. Then piston 52 influenced by action 'ofspring 53 returns into'the left hand end position and themachin'e starts to operate again.

What I claim and desire to secure by Letters Patent is:

1. A torque regulator for motors of the class described, comprising a motor driven shaft section, a driving shaft section movably mounted with respect to the said motor driven shaft section and connected to the unit to be driven, coupling means between the said two shaft sections engaging at least one of the said shaft sections and adapted to be displaced axially with respect to at least one of the said shaft sections by the torque transmitted by the coupling means from the motor driven shaft sec tion to the driving shaft section, a bolt connected to the said coupling means and extending co-axially to the shaft sections, a spring means counteracting the axial displacement of the said coupling means and said bolt, and power supply means to the motor controlled by the displacement of said bolt.

2. A torque regulator for motors of the class described, said torque regulator comprising a motor driven shaft section, a second shaft section rotatably but not slidably mounted with regard to the said motor driven shaft section and connected to the unit to be driven, between the said two shaft sections a coupling means rotatably and slidably arranged with regard to the said shaft sections and having at least one helical key adapted to fit in a corresponding groove provided in a hollow portion of at least one of the two shaft sections, a bolt connected to the said coupling means and extending co-axially to the said shaft sections, a spring means counteracting the axial displacement of the said coupling means and the said bolt, a valve means connected to and controlled by the said bolt, and power supply means to the motor controlled by the said valve means.

3. A torque regulator for motors of the class described comprising a motor driven shaft section, a driving shaft section movably mounted with respect to the said motor driven shaft section and connected to the unit to be driven, coupling means between the said two shaft sections having at least one helical key adapted to fit in the corresponding groove provided in a hollow portion of at least one of the two shaft sections, and adapted to be displaced axially with respect to at least one of the said shaft sections by the torque transmitted by the coupling means from the motor driven shaft section to the driving shaft section, a bolt connected to the said coupling means and extending co-axially to the said shaft sections, a spring means counteracting the axial displacement of the said coupling means and the said bolt, and power supply means to the motor controlled by the displacement of said bolt.

4. A torque regulator according to claim 3, in which the power supply means is controlled by a valve means connected to the bolt, the valve means comprising a piston displaced by the bolt, and spring means counteracting the displacement of the said piston.

5. A torque regulator according to claim 4, in which the said bolt and the said valve means have a certain space between them in one of their end positions the said space bein adjustable by means of a stop attached to at least one of them and fixed in an adjusted position by a nut.

6. A torque regulator according to claim 4, in which the power supply is air under pressure entering through an air supply passage and in which the piston travels with a control edge over the air supply passage to close the passage, the passage remaining closed until the air pressure is relieved.

permit the air suppl passage piston to move to openthe air supply passage.

8. A torque regulator of the class described, comprising a motor driven shaft section connected to the motor as by means of gears, a second shaft section rotatably and slidably mounted with respect to the motor driven shaft section and connected to the unit to be driven as 'by means of gears, a coupling means unitary to the said second shaft section and engaging the motor driven shaft section and adapted to an axial displacement together with the said second shaft ection with respect to the said motor driven shaft section depending upon the torque transmitted by the coupling means from the said motor driven shaft section to the said second shaft section, a bolt fixed to the said coupling means and the said second shaft section and extending co-axially to the said shaft section, a spring means counteracting the axial displacement of the said coupling means and the said bolt, and means connected to the said bolt for controlling power supply means to the motor according to the displacement of the bolt.

9. A torque regulator of the class described, comprising a motor driven shaft section connected to the motor as by means of gears, a second shaft section rotatably and slidably mounted with respect to the motor driven shaft section and connected to the unit to be driven as by means of gears, a coupling means unitary to the said second shaft section and engaging the motor driven shaft, having at least one helical key adapted to fit in a corresponding groove provided in a hollow portion of the said motor driven shaft section, and adapted to an axial displacement together with the said second shaft section with respect to the said motor driven shaft section depending upon the torque transmitted by the coupling means from the said motor driven shaft section to the said second shaft section, a bolt fixed to the said coupling means and the said second shaft section and extending co-axially to the said shaft section, a spring means counteracting the axial displacement of the said coupling means and the said bolt and means connected to the said bolt for controlling power supply means to the motor according to the displacement of the bolt.

10. As a subcombination in a torque-controlled motor, a driving shaft driven under controllable power, a driven shaft connected to the driving shaft by a coupling which together with the driven shaft is axially displaced relative to the load applied to the driven shaft, the axially displaced shaft simultaneously controlling a power control means according to the degree of displacement.

References Cited in the file of this patent UNITED STATES PATENTS 824,425 Johnson June 26, 1906 2,402,972 Mitchell July 2, 1946 2,569,244 Larson Sept. 25, 1951 

